Fix mypy signature.

Author: Peter Amstutz

cwltool/job.py

@@ -99,7 +99,7 @@ def deref_links(outputs):  # type: (Any) -> None
             deref_links(v)
 
 def relink_initialworkdir(pathmapper, host_outdir, container_outdir, inplace_update=False):
-    # type: (PathMapper, bool) -> None
+    # type: (PathMapper, Text, Text, bool) -> None
     for src, vol in pathmapper.items():
         if not vol.staged:
             continue